Polishing formulations for the chemical mechanical planarization (CMP) of integrated circuit wafers, as well as polishing compounds for high technology optical components typically consist of an aqueous dispersion of solids (the abrasives) combined with a variety of chemical constituents. Such commercial materials typically are sold in several parts, one containing the abrasive component in a concentrated form and the other part containing the chemical component(s) in a concentrated form. As the technology of CMP polishing has become more critical, complex chemical and abrasive systems have been developed. These aqueous formulations must exhibit long shelf life, and good stability so that the materials do not change while in storage, thus becoming useless for their intended purpose. For example, if a dispersion of solids is stored and the solids settle in the container to a hard or difficult to mix sediment, the dispersion is no longer readily usable by the customer.
Many attempts to make one component systems in which the chemical as well as the abrasive components are mixed in one liquid system have proven problematic. The problems occur because the presence of the chemical constituents is rarely conducive to forming stable solid dispersions, consequently the solids settle to the bottom of the container and require subsequent redispersion prior to use. This presents many problems to the end user. If the solids have settled into a difficult to redisperse sludge, the chances of utilizing all of the settled material are not good because it will stick to the container. Furthermore, shaking or stirring a large container such as a drum or tote is impractical.
The ideal concept would be to make a slurry exactly as the final end user would use it, and then xe2x80x9cfreeze it in timexe2x80x9d so that it will be exactly as the end user wants it, three or even six months after the slurry is made. Since the main reason for instability is due to the aqueous dispersions that these slurries are sold as, it would be reasonable to assume that if one could eliminate the xe2x80x9caqueousxe2x80x9d part of the system, the stability issues for both the chemical and abrasive constituents would be minimized.
A dry particulate solids composition comprised of a chemical-mechanical polishing slurry comprising submicron abrasive particles is provided which has had substantially all water removed therefrom and which may be reconstituted into a chemical-mechanical polishing slurry ready for use.
A method for chemical-mechanical polishing is provided comprising the steps of:
a) providing a polishing pad;
b) introducing a polishing fluid comprising submicron abrasive particles between said pad and a workpiece;
c) producing relative motion between said pad and said workpiece; wherein said polishing fluid has been reconstituted from a dry particulate solids composition comprised of a chemical-mechanical polishing slurry comprising submicron abrasive particles which has had substantially all water removed therefrom.
In addition to submicron abrasive particles, the dry particulate solids composition of this invention may comprise an oxidizing agent, a complexing agent, a surface passivating agent, a surfactant, a dispersant, or any other type of compound used in slurries for chemical-mechanical polishing.